The molecular biology core seeks to provide center investigators with [1] a centralized resource for oligodeoxynucleotide synthesis, chiefly to facilitate the acquisition of primers for use in polymerase chain reaction amplification, sequencing, and mutagenesis, [2] a library of useful primers, already made and characterized for these purpose, [3] centralized access to a library of useful plasmid constructs, for use in cloning, eukaryotic selection, expression, reporting, and use as reference and control agents, including many proviral plasmids, [4] a central reference resource for quantitation of viral RNA and DNA, including a central reference QC-PCR facility, supplying primers, constructs, and reference reagents and samples, as well as performing assays as a service, and [5] a central data acquisition and sharing of sequence information. In order to accomplish these goals the core proposes: [1] to utilize a dedicated synthesizer for the preparation of oligonucleotides, [2] to perform purification of synthesized oligonucleotides by polyacrylamide gel electrophoresis, [3] to synthesize frequently used primers on a large scale, aliquoting and dispensing these with quality controls, [4] to supply the data analysis core primer information, for dissemination to center investigators, [5] to perform the transformation, preparation and purification of a variety of frequently used plasmids as well as performing custom plasmid preparation on a recharge basis, [6] to maintain secure bacterial and plasmid stocks for center investigators, [7] to perform QC-PCR for genomic and spliced HIV-1 and HIV-2 messages and DNA PCR for provirus with internal standards, providing primers and plasmid constructs for QC-PCR to center investigators, participating in the custom design of QC-PCR systems, as well as standardized samples, samples, and standardized RNA and DNA preparations, on a recharge basis, and [8] sequencing of PCR products for analysis of HIV genomes, on a recharge basis when exceeding funded capability.